Earlier quoted context omitted.
Surely it can't have been genuine if people are dismissing her in this way? Texting "I'm sick not this time" and then no more communication ever?
Empirical observation #1: A student said “I’m sick today. I can’t make the lesson. I’ll contact you later,” Empirical observation #2: That student didn't contact her later including not replying to emails she sent afterwards. There's also a direct consequence of empirical observation #2: The lessons could not continue. Assumption #1: The student pretended to be sick. This student could have been actually sick. We hav…
That said the author maybe does see the fakeness ("They want it to feel like a friendship" ie. not be an actual friendship, just something like that feels like it, fine line I know but it's desired performance vs actual emotion). However she still thinks they "owe" her something.
But English lessons in Japan must be like... I dunno, grocery shopping to us. I'm guessing tutoring is more common in Japan than in North America. When you decide never to go to a particular grocery store, you don't give long heartfelt goodbyes. You just stop going.